I see both sides really. I understand that it's good to get a feel for used prices by what's sold already. But that being said, each item is so individual that sometimes previous asking prices could be misleading. (Like various sp's or die sizes on the same model cards)

But on the other side, I agree with crazyhorse. The asking price may not always be the sell price. Or in some cases it could be a straight trade. Top that with all the people sending PM's if the price is there, even if there's a sold sign right next to it, and I end up just replacing the price. But, that being said, I don't mind telling people what they sold for (in most cases) if I get a PM asking.